#include <iostream>
using namespace std;
class f
{
public:
    virtual void show(){
        cout<<"f"<<endl;
    }
};
class z1 : public f
{
public:
    void show(){
        cout<<"z1"<<endl;
    }
};
class z2:public f
{
public:
    void show(){
        cout<<"z2"<<endl;
    }
};
int main()
{
    f *f=new z1;
    f->show();
    return 0;
}